Rock drill



June 10 1969 zr-:N'Jl MoRlsr-IITA AET AL ROCK DRILL Sheet Filed Dec. 12, 1967 June 10, 1969 zENJl MORISHITA ET Al- 3,448,817

' ROCK DRILL Filed Dec. 12,1967 sheet ,8 of s Fig-.4.

ZENJI MoRlsHlTA man summa KAwArA. Names June 10, 1969 zENJl MoRlsHlTA ET AL 3,448,817

ROCK DRILL Filed Dec. l2. 1967 l Sheet 3 of 5 ZENII MORISHITA Aun SHoJmo KAWATA.|nvEN1-m hmmm mi, JMA.

3,448,817 ROCK DRILL Zenji Morishita, 698, Aza-Takemukai, Okumyokji, Sumaku, Kobe, Japan, and Shojiro Kawata, 127, Higashiyama-cho, Ashiya, Japan Filed Dec. 12, 1967, Ser. No. 689,845 Int. Cl. E21b 1/00; E21c 3/00, B25d 9/00 U.S. Cl. 173-119 12 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to a rock drill tool for crushing rock and concrete or the like, and includes a lmainhousing in which a spring-loaded heavy duty hammer member is reciprooably moved vertically against the expansive force of a repeatedly compressed drive spring disposed above said hammer within the housing. A striking rod is mounted belo'w the hammer for limited vibrating action when hit on the upper end yby the hammer.

The hammer is driven reciprocably by a power driven rotary cam engageable :by a rotatable cam follower wheel carried on the side of the hammer. The rotary cam and prime power source are mounted -with novel Vibration reducing means therebetween and on the side of the main tool housing with the cam follower wheel projecting through and operable within mutual slots in said housings. Novel lubricating means are mounted on and in direct conjunction with the tools main housing to provide for comibined lubricating and vibration dampening of the hammer and striking rod, thereby providing a more endurable tool. Various type prime mover motors utilizing electric or fluid pressure means, including compressed air or hydraulic oil, may be -used t power the tool. Additionally, the motor means could be -mounted remote of the tool body per se, if desired.

The present invention relates to a rock drill for crushing a rock, a concrete and the like.

The usual rock drill is mainly composed of the cylinder-piston system, in ywhich compressed air is used, so that it necessitates a power source, made of a pump for compressing air, a tank for the compressed air and the like, its treatment being troublesome and its cost is dear. In the present invention a rotary prime mover motor is used which does not necessarily require the application of the compressed air as mentioned above. The power source of the rock drill according to the present invention may be either a compressed air motor or a hydraulic oil pressure motor and is not limited to the use of only an electric motor. By providing that various power-systems can be applied is an important advantage of this invention.

The present rock drill invention uses one of t'he abovementioned rotary prime motors, by which a 0am is turned and a striking rod, which is adapted to be pressedv against |a rock, a slab of concrete and the like, is struck by means of the hammer, capable of rising and falling responsive to the lifting 'action of the cam and a spring biased dropping action, and embodying an exceedingly simple construction, permitting easy manufacturing without the need of highly accurate work pieces as previously required for the prevention of leaks as used in the piston and cylinder system. Also, it is easily manipulated because of its small size land relatively light weight. The details providing such advantages as mentioned above will be illustrated about various examples shown in accompanying drawings.

FIGURE l is a longitudinally sectional elevation view of the main part of the rock drill according to the present invention.

dUnited States Patent O 3,448,817 Patented June 10, 1969 ICC FIGURE 2 is a longitudinally sectional and enlarged view of the valve part of the oil tank secured to the upper portion of the rock drill according to the present invention.

FIGURE 3 is an enlarged, fragmentary longitudinally sectional view of the cam part of the rock drill according to the p-resent invention.

FIGURE 4 is an enlarged fragmentary, longitudinally sectional view 0f the installing portion of the striking rod.

FIGURE 5 is an enlarged longitudinal section view 0f the bearing portion of the cam shaft.

FIGURE 6 is an elevation view of the guide hole for the slider.

FIGURE 7 is an enlarged longitudinal section view of the coupling part rbetween the cam shaft and the driving shaft.

FIGURE 8 is an enlarged longitudinally sectional view of the main part sho/wing another embodiment of the rock drill 'according to the present invention.

FIGURE 9 is a transverse section view taken along the line A-A in FIGURE 8.

In the drawing figures, there is depicted a tubul-ar body 1 having a circular cross section, to the upper portion of which is mounted an oil tank 2. The oil tank 2 is xed on the tubular body 1 by screwing the female screw formed inside of the tubular portion of the lower portion thereof around the male screw formed at the outer periphery of the upper end of the tubular body 1. But, it may be attached |as by welding or any other method.

At the bottom of the oil tank 2 is an oil hole 3 leading to the tubular body 1 and a valve member 4 which opens and closes said oil hole 3 is mounted for vertical reciprocable movement. The upper end of the valve member 4 is slidably inserted through a central aperture of a threaded pipe 5 or cap screw disposed in a complementally threaded hole in the top plate of the tank 2. The upper end of said valve member 4 protrudes beyond the upper portion, and to the upper end thereof is fixed a nob 6. Between the lower end of the threaded pipe 5 and a collar lixedly mounted to the lower portion of the valve member 4 and in contact therewith are both ends of a compressed coil spring 9, encircling member 4 and by which the low end of the valve member 4 is biased to close the oil hole 3. By turning of the threaded pipe 5 the resilient force of the spring 9 is adjustable. Also, to the top portion of the tank 2 is formed an oiling opening having a seal screw 21. Inside of the tubular body 1 is -tted vertically reciprocable, spring-loaded hammer 8. A coil spring 7 is compressed between the upper end of said hammer and the bottom of the oil tank 2, mounted thereabove on the tubular body 1, to push the hammer 8 downwards. The hammer 8 ascends and descends through rolling contact of a plurality of anti-friction steel balls 11, disposed in grooves 10 near opposite ends of said hammer, and thereby the outer periphery of the hammer 8 and the inner periphery of the tubular body 1 never come in contact.

Within an elongated hole 12 formed at the bottom of the tubular body 1 there is disposed a vertically reciprocable upper half portion of a striking rod 13. The upper end of the striking rod 13 protrudes inside of the tubular body 1 and fits idly into the aligned central holes of a plurality of washers 14 disposed on the bottom of the tubular body 1. Between the outer peripheries of the washers 14 and the inner periphery of the tubular body 1 a gap exists and the washers 14 move up and downwards guided against the tubular body 1. Around the outer periphery of the lower end of the tubular body 1 is formed a male screw, around which is screwed a female screw formed at the inner periphery of a threaded pipe cover 15, and into a central hole 17 located in the bottom end wall of the threaded pipe cover the lower half of the striking rod 13 freely inserted. At the middle part of the striking rod 13 a collar 16 is formed preferably integrally with the upper and the lower halves projecting oppositely therefrom, with said collar 16 being normally positioned in an adjustable space between the lower end of the tubular body 1 and the bottom of the adjustable threaded pipe cover 15. Accordingly, the vertically movable range of said striking rod 1'3 is limited.

Between a notch 18 formed at the upper edge of the threaded pipe cover 15 and a concaved hole 19 formed at one part of the outer periphery of the lower portion of the tubular body 1 opposite ends of a coil spring 20 are fitted, and thereby the threaded pipe cover 15 can be prevented from loosening. Also, fitted between said tank 2 and the tubular body 1 is another coil spring 20l as mentioned above, and its opposite ends are similarly fitted into a notch of the lower portion of the tank 2 and into a concaved hole of the tubular body 1 to prevent its rotation.

To a side face of the middle part of the tubular body 1, there is fixed a casing 22, in which a cam shaft 23 is rotatably mounted. Fixed to the cam shaft 23 is a tubular cam 24, the upper edge of which is formed to be a helically slanting face of the cam. The slanting face 25 of the cam is made to be gradually steeper from the beginning end a toward the terminal end b and to have a vertical step between the terminal end b and the beginning end a. The cams 24 may be provided with two different types of spiral cam= surfaces 25 as viewed in radial cross-section; one having an inclined surface higher at the inner or shaft 23 side, as shown in FIGURE 3 and another being substantially horizontal, as shown in FIGURES l and 5.

In the overlapped portion of the casing 22 and the tubular body 1 there is formed a rectangularly elongated guide hole 26, into which is slidably fitted a square-shaped slider 28 rotatably mounted on a mounting shaft 27 lfixed into the side face of the hammer l8. On the shaft end protruding beyond the slider 28 a roller 29 is rotatably mounted to engagingly follow the slanting face 25 of the cam.

Said guide hole 26 is inclined from the vertical or sloped such that the slanting face 25' of the cam is rotated by coming in contact with the roller 29 as shown in FIG- URE 6. However, it is to be noted that the guide hole 26 may be formed fully upright, wherein the outer periphery of the roller 29 for engaging slanting face 25 of the cam as in FIGURE 3 is made to be spherical and that for such slanting face 25 of the cam as in FIGURES l and 5 the outer periphery of the roller 29 is to be of a straight cylindrical face.

The lower portion of the cam shaft 23 is preferably stepped down to a smaller diameter portion 30, around which the inner trace of a radial ball bearing 31 is fitted and with the outer race of said bearing 31 being fitted into the lower, recessed portion of the casing 22. At the lower end of the *bearing portion of the casing 22 there is formed a threaded hole, into which an adjustable screw 32 is screwed. In a concave upper face of the inner end of said adjustable screw 32 there is mounted a receiving piece 33, on which is mounted a steel bearing ball 34, which is also fitted into a complemental recess of the lower end of the cam shaft 23. Said receiving piece 33 is of a convex disc-like form and made from hard material, such as a stone. A radial roller bearing may be used instead of said radial ball bearing 31.

On the casing 22 is mounted a prime mover 35. It is an electric motor in this case, and a shaft 36 leading from the rotor thereof is coupled to the'cam shaft 23. The shaft 36 and the cam shaft 23 are coupled, as shown in FIGS. l and 7, by means of coupling plates 37, 38; and with a tapered portion of the lower end of the shaft 36 closely fitting into the central complementally tapered hole of the coupling plate 37, the shaft 36 and the coupling plate 37 become jointed' as one body. Additionally, a plurality of pins 39, mounted to the lower face of the coupling plate 37 in a projecting manner at uniform distances from the center of the shaft, are fitted into elastic tubes 40, made from elastic body such as a rubber, which are recessed into a like plurality of holes formed to the coupling plate 38, and a square-shaped hole provided at the center of the coupling plate 38 receives a complemental square-shaped shaft portion at the upper end of the cam shaft 23. Accordingly, the shafts 36, 23 are not coupled directly, but are semi-resiliently coupled by said fitting between the pins 39 of the coupling plate 37 and the elastic tubes 40 of the coupling plate 38'.

In operating the rock drill according to the present invention, initially, the lower end of the striking rod 13 is placed against an object, and then the casing 22, the tubular body 1 and the like are held by means of a handle 41 mounted to the prime Vmover 35. Then, when the prime -rnover 35 starts by switch operation and the cam shaft 23 is rotated along the arrow direction, the roller 29, normally positioned at the beginning end a of the slanting face 25 of the cam at start, is rotated and follows on the slanting face 25 of the cam responsive to the rotating of the cam shaft 23 and gradually ascends. Simultaneously, the hammer 8 is gradually ascended along with said roller 29 against the expansive force of the coil spring 7.

When the roller 29 passes off the high terminal end b immediately after completely following the slanting face 25 of the cam, the roller 29 and the hammer 8 together are rapidly descended owing to the powerful expansive force of the spring 7, whereupon the upper end of the striking rod 13 is violently struck -by the lower end of said hammer and the lower pointed end of the striking rod 13 is thrust into the object.

The roller 29 being descended from the terminal end b of the slanting face 25 of the cam as mentioned above is again put on the beginning end a of the slanting face 25 of the cam and is lifted up by the slanting face 25 of the cam similarly as above-mentioned. Thus, by rotation of the cam 24 the above-mentioned work is repeated; the hammer y8 strikes repeatedly the upper end of the striking rod 13 and the object is crushed by the striking rod 13. Each part exhibits the following action and effect in such work.

When the hammer 8 reciprocates, the steel balls 11 come in rolling contact with the inner periphery of the tubular body 1 to decrease frictional resistance, while, the valve member 4 in the tank 2 is -vibrated vertically by a violent vertical vibration produced inside of the tubular body 1, and the oil hole 3 is opened and closed intermittently, with the oil in the tank 2 being dropped from the oil hole 3 and lubricates between the tubular body 1 and the hammer 8, so that the hammer 8 can be reciprocated smoothly.

When the hammer 8 falls and strikes the upper end of the striking rod 13, the upper end of the striking rod 13 forced down or into the uppermost end of the stacked washers 14, and the hammer 8 strikes against the upper end of the washers 14. Meanwhile, the oil, dropped from the tank 2, collects in the lower portion of the tubular body 1 and forms the oil film between individual Washers 14. When the upper end of the Washers 14 is struck by the hammer 8, the individual oil-coated washers 14 are compacted and perform a buffer or dampening action scattering the oil there between. Thus, since the buffer action is carried out by help of the oil contained between the washers 14, the present device is more endurable of the violent impacts and defrays concentrating all of the stress on only the coil spring which, as a result thereof, never suffers damage. Also, since part of the oil flows gradually into the hole 12 and lubricates the striking rod 13 and the hole 12, wear of this part is also remarkedly decreased. And, when the lower end of the i hammer 8 comes in contact with the washers 14, the slider 28 is arranged so as not to reach and jar against the lower end of the Iguide hole 26.

The roller 29 and the slider 28 are lifted up by the slanting face of the cam being rotated, so that when the slanting face 25 of the cam moves in the direction of the arrow in FIGURE 6 and lifts up the roller 29, an obliquely upward right hand force component acts against the roller 29. If the guide hole 26 is sloped to the right along an obliquely upward direction as shown in FIGUR-E 6, friction resistance becomes greater during the lifting of the slider 28, and the reciprocal movement of the slider 28 becomes smooth. The slanting face 25 of the cam is made to be dilferent in its inner and outer circumferential velocities; if the slanting face 25 of the cam is sloped as its inner side is higher as in FIGURE 3 and the outer periphery of the roller 29 is made to be spherical, the slanting face 25 of the cam and the outer periphery of the roller 29 come theoretically in point contact and their movement gets smooth without producing friction or sliding owing to difference of the circumferential velocity. Due to the fact the roller 29 is in pressing contact on the slanting face 25 of the cam, a partial load is applied to the cam shaft 23. If the lower end of the cam shaft 23 is received or provided with a conventional thrust bearing, there is the risk of early damage of the bearing, But, if the lower end of the shaft 23 is provided or received with the combination of the radial ball bearing 31, the steel ball 34 and the hard receiving piece 33, so that the load is dispersed, a partial load is received by the bearing 31, and the vertical component of the load is received by the steel ball 34 and the receiving piece 33, respectively. Therefore, damage to the bearing portion is prevented. The cam shaft 23 is violently vibrated due to the inherent operation of the roller 29 repeatedly dropping on the beginning end a from the terminal end b and so, due to the unique buffered construction and assembly of the coupling plates 37 and 38 and related components at the coupling portion to the shaft 36, little of the vi-bration of the cam shaft 23 is transmitted to the shaft 36. Therefore, potential bad effects due to vibration of the rotor as mounted to the shaft 36, or the bearing of the shaft 3-6 and the like hardly occur. Besides, the main body of the prime mover is not directly tixed to the tubular body 1 and the casing 22, but may be mounted through vibration-proof :ruibber to separate the main body of the prime mover 35 from vibration.

Also, the prime mover used in the present invention may be any type, such as an electric motor, an oil pressure motor, a compressed air motor and the like. Furthermore, the prime mover may be mounted to another body, with the prime mover and the cam shaft being coupled with a iiexible shaft.

In the embodiment of FIGS. 8 and 9, the hammer and prime mover mechanism, not shown therein, are similar to that shown in conjunction with FIGS. 1-6, inclusive.

In the embodiment of FIGURES 8 and 9, the striking rod 13 differs from the previous form in that it is made to be rotated.

Namely, a portion depending below the collar 16 of the striking rod 13 is for-med as a hexagonal engaging portion 42 and is reciprocably disposed in complemental hexagonal engaging hole 44 of a :rotor 43 and is rotated together with said rotor 43.

The rotor 43 is formed of two parts as shown in FIG- URE 9 which are coupled to form one tubular shape, by means of a pair of bolts 45. Therefore, when the bolts 45 are removed, the rotor 43 is divided into the two parts.

Around the outer periphery of the lower part of the tubular body 1, in lieu of exterior screw threads, there is rotatably disposed a cylinder 46, the lower part of which is supported on body 1 -so as not to slip out downwardly as by a stop ring 47, fitted to be attachable and detachable into a peripheral groove of the outer periphery of the lower end of the tubular body 1.

To the upper portion of the cylinder 46 is -xed a gear '48, with which is meshed a gear 49 iixed to the lower end of the cam shaft 23 the latter of which protrudes beyond the lower end of the casing 22.

Said rotor 43 is iitted around the outside of the cylinder 46, and the tightening force of the bolts 45 couples together as one body the rotor 43 and the cylinder 46.

This embodiment further contemplates and discloses a detachable tip portion '50 to be removably attachable to the lower end of the striking rod 13; and, in this case, the upper tapered end of the tip portion 50 is fitted into the tapered hole of the lower end of -the striking rod 13. Further, a slender hole 51 transversely formed at the lower end of the striking rod 13, passes through the tapered hole, as shown in lFIG. 8, and the tip portion 50 is removed by a simple lever or wedge inserted into the slender hole 51. Additionally, adjacently below the tapered tip portion 50 is formed a male screw thread, around which a lock nut 52 is screwed, and by utilizing said nut '52 the tip portion 50 is made to be removed.

In this case,` the striking rod 13 may be made from one material similarly to that of other example.

In this embodiment, together with the rotating of the cam shaft 23 gears 49 and 48 are rotated, thereby rotatling with gear 48, the cylinder 46, the rotor 43 and the striking rod 13. At the same time, the hammer 8 repeatedly strikes the upper end of the striking rod 13 as described hereinabove and drives the tip portion 50 into the object.

Because the striking rod 13 slides with the engaging portion 42 in the hole 44 portion, a striking force owing to the hammer 8 is positively transmitted from the striking rod 13 to the tip portion 50.

In this example, the striking rod 13 is rotatably driven into the object so that crushing action of the object is achieved.

We claim:

1. Ina power impact hammer tool, the combination comprising:

(a) a main elongated tubular body for housing a movable spring biased hammer;

(b) a movable heavy duty hammer reciprocably dis'- posed in said main body;

(c) lubricating means mounted on and closing the upper end of "said tubular body, and adapted to dispense lubricant into said body responsive to reciprocably induced vibration of the hammer;

(d) a striking rod and means associated therewith and with the lower end of said tubular body to provide limited vertical movement of said striking rod responsive to impact of the hammer;

(e) a second housing affixed to a lateral side of the main body including means for improved rotatable disposition therein of a rotary cam shaft;

(f) a rotary -cam shaft having a cam body disposed intermediate its ends, with its axis parallel with the axis of said tubular body, and said cam body having a generally spiral shaped cam track thereon;

(g) cam follower means mounted on and projecting laterally from the hammer through vertically elongated apertures in the respective housings for following engagement with said spiral cam track;

(h) prime power driving means mounted exteriorly of said main body and operably connected with the upper end of said cam shaft; and

(i) resilient vibration-dampening coupling means -interconnecting the power driving means and the upper end of said cam shaft.

2. A power impact hammer tool as defined in claim 1,

further including:

(a) supplemental v-ibration dampening means including a plurality of washers loosely stacked on the upper end of the striking rod within the lower part of said main body and said washers being well lubricated from said oil,

(b) said upper terminal end of the striking rod normally projecting above the top of said washers by an amount corresponding essentially to and not exceeding the limited travel of said rod, whereby when said rod is driven downward by said hammer, said hammer impacts against said lubricated stack of washers to help disperse and absorb the vibration thereof by the washers compacting and temporarily forcing the lubricant oil from between adjacent washers.

3. A power impact hammer tool as defined in claim 1, wherein the resilient vibration-dampening coupling means of paragraph (i) includes:

(a) coupling plates aixed respectively to the adjacent ends of the rotary cam shaft and the drive shaft of the prime power driving means;

(b) pin means projecting from one of said coupling plates toward the other; and

(c) the other coupling plate having pin receiving apertures alignable with said pins and resilient tubular cushio-ning members in said apertures to receive and vibrationally insulate said pins projecting therein.

4. A power impact hammer tool as defined in claim 1, further including a drive spring compressibly disposed in said main body engageable between the upper end of said hammer and said lubricating means; and wherein said lubricating means of paragraph (c) thereof includes an oil reservoir tank having a bottom wall which closes off the top of said main body and against which said spring engages; a vibratory valve member having a lower end normally engageable in an oil-dispensing aperture in the bottom wall of said oil tank and communicating with said main body, said valve member including means associated therewith to facilitate intermittent opening and closing of said aperture responsive to reciprocable motion of said hammer during operation of the tool.

5. A power impact hammer tool as defined in claim 1 wherein said hammer is of elongated, heavy duty form and includes annular grooves near opposite ends and having antifriction ball bearings disposed therein for engaging the sides of said main body during reciprocable movement of said hammer.

6. A power impact hammer tool as defined in claim 1 wherein the means in paragraph (d) thereof include an internally threaded cover member adjustably mounted on the lower end of said main body, said cover member having an apertured end wall through which said striking pin slidably projects, said end wall being adjustably spaced from the lower end of said main body, said striking pin having an enlarged collar projecting annularly from said pin intermediate its ends, and said collar intermittently engageable between said lower end of said main body and said end wall of said cover member responsive to vibratory reciprocal movement of said hammer and pin.

7. A power impact hammer tool as defined in claim 1 wherein the cam follower means in paragraph (g) thereof includes a roller mounted on the end of a shaft projecting from said hammer and said roller engageable by said rotary cam tract to lift said hammer.

8. A power impact hammer tool as defined in claim 1 wherein the cam follower means in paragraph (g) thereof include a roller mounted on the end of a shaft projecting from said hammer, said roller having a generally spherical contoured surface; and said cam track in paragraph (f) thereof is canted with the high side being closer to the center cam shaft, the outer peripheries of said spherical surface of said roller engageable by said canted track responsive to rotation of said cam shaft to facilitate lifting of said hammer.

9. A power impact hammer as defined in claim 8 wherein a slider member is interposed on said shaft between said roller and said hammer, said slider complementally shaped to slidingly engage with the sides of the elongated apertures in said main body and said second housing, and said elongated apertures are inclined with respect to the vertical in the direction of rotation of said rotary cam body; said slider adapted to travel in said inclined apertures to facilitate the lift moment of the hammer.

10. A power impact hammer as defined in claim 1 wherein the means in said second housing of paragraph (e) thereof for improving the rotatable disposition of said rotary cam shaft therein include ball bearing means disposed radially adjacent upper and lower end areas of said shaft, and ball bearing means interposed between the lower axial end of said rotary cam shaft and a lower end portion of said second housing.

11. A power impact hammer as defined in claim 10 wherein the latter-mentioned ball bearing means includes a spherical recess in the end of said rotary shaft and in adjustably removable means axially aligned therewith in said lower portion of said second housing; and a ball bearing interposed therebetween.

12. A power impact hammer as defined in claim 1 wherein said rotary cam shaft has its lower end projecting below said second housing; and wherein said main body includes rotatable sleeve means on the lower end thereof and through which said striking pin projects; complementally interengaging means on said sleeve and said pin to enable said pin to rotate with said sleeve; relatively rotatable interengageable drive means on said projecting lower end of said rotatable cam shaft and on the outer periphery of said rotatable sleeve, to facilitate rotation of said striking pin simultaneously with its reciprocable action during operation of said tool.

References Cited UNITED STATES PATENTS 2,006,065 6/1935 Blake 173-123 2,501,542 3/1950 Sheldon 173-123 3,107,083 10/1963 Pewthers 173-123 3,163,237 12/1964 Fulop 173-123 3,302,732 2/1967 Roll 173-123 a JAMES A. LEPPINK, Primary Examiner.

U.S. Cl. X.R. 173-123 

